There are several rules for smart shopping at the grocery store, but one is to pay attention to the price per pound. Consumers are often tricked into thinking they’re getting a deal when they’re comparing two items that seem the same, but are actually different.

That’s the case with those rotisserie chickens at the supermarket. They look like a good deal, the same price as the raw whole chickens, but pre-cooked. But are you really getting the same thing?

Though it may not seem that way to the consumer’s eye, rotisserie chickens tend to the small side—maybe two to two and a half pounds. The broiler chickens that sell for the same price are more like four and a half pounds. Even after they’ve been cooked—a process that, according to the U.S. Department of Agriculture, reduces their weight by a little more than 20%—broiler chickens are still much bigger.

After buying rotisserie and uncooked chickens at a bunch of national chains and then comparing the per-pound cooked cost, except for Costco and Smart & Final, the savings from home cooking could be substantial.

On the other hand, as a takeout meal, it’s a better deal than a lot of fast food places and potentially healthier too.